Hydraulic brake



Sept, 17, 1946 H Q H|| 1 i 2,407,699

HYDRAULIC BRAKE Filed sept. 2o, 194s 2 sheets-Sheet 1 INVENTOR HENRY C. HILL A TTORNEY sept. 17, 194e. H. c. HILL 2,407,699

HYDRAULIC BRAKE Filed Sept. 20, 1945 2 sheets-sheet' 2 l MVENTOR l 1 Ei E A v HENRY C. HILL.

. ATTORNEY Patented Sept. 17, 1946 HYDRAULIC BRAKE Henry C. Hin, Montclair, N. J., assigner to Wright` Aeronautical Corporation, a corporation of New York Application September 20, 1943, Serial No. 503,144

This invention relates to a hydraulic clutch or brake and is particularly directed to a uidoperated plate clutch or brake in which the engaging surfaces are lubricated by the actuating uid. The invention is illustrated and described in connection with and as forming a part of the variable speed transmission and associated brake disclosed in the copending application of Hill et al., Serial No. 461,026, led October 6, 1942, now Patent No. 2,368,835, Feb. 6, 1945. However, as will appear from the following description, the invention is not limited to this specific use, but is of general application and may be used either with a frictionally engaging clutch or brake.

The aforementioned copending application'of Hill et al. discloses a brake which, when engaged, locks up a cage carrying a plurality of double planet pinions to provide a gear drive through the pinions and which, when disengaged, permits rotation of the pinion carrier. The design of the transmission is such that upon rotation of the pinion carrier, the centrifugal force acting on the pinions is of sumcient magnitude to lock the pinions about their journals, thereby providing a direct drive connection. In order to effect a return to the gear drive through the pinions, the brake is again engaged to prevent rotation of the pinion carrier. In practice it has been found thatthe frictional forces locking the pinions about their journals are of such magnitude that the brake must exert excessive friction torque to break the pinions loose from their journals in order to secure the pinion carrier against rotation. This excessive friction torque has caused considerable scuiiing of the brake plates and it is an object of this invention to provide means to lubricate the friction engaging surfaces of the brake in order to eliminate or minimize this scufng.

4It is a further object of the invention to provide a fluid actuable brake in which the friction 11 Claims. (Cl. 18S-152) surfaces are lubricated by the actuating uid.

A still further object of the invention Vis to provide a lubricated brake or clutch in which there is a continual now of lubricant over the friction surfaces while slippage occurs and in which the iiow of lubricant automatically ceases when the friction surfaces become clamped together. Another object of the invention is to provide a selfsealing lubricated clutch or brake in which the clutch or brake is constructed to insure uniform lubrication over the entirefriction engaging surface.

Other objects of the invention will become apparent upon reading the annexed 'detailed de- 2 scription in connection with which:

Fig. l is an axial section through the invention,

Fig. 2 is a view along line 2-2 of Fig. l, and

Fig. 3 is an enlarged sectional view taken along line 3-3 of Fig. 2. i

Referring to the drawings, an engine-driven shaft I Il is drivably connected to a gear I 2 by means not shown and a driven shaft I4 journaled about the drive shaft is adapted to be driven by the gear I6. An annular cage I8 is concentrically disposed about the shafts I0 and I4 and is provided with a plurality of double planet pinions 20 journaled about shafts 22 carried by the cage. Each of the double pinions 20 is meshed with one ofthe gears I2 and I6 whereby, when the cage or pinion carrier I8 is held stationary, the double pinions provide a step-up drive between the gears I2 and I6.

In order to hold the pinion carrier stationary a multi-plate brake 24 is provided about the external periphery of the pinion carrier. As more fully described in the aforementioned copending application, when the pinion carrier is released the design is such that the rotation of the pinion carrier with its pinions subjects the pinions to a centrifugal force sufficient to lock these pinions against rotation about their journals 22. Therefore, upon release of the brake 24 'a direct drive is provided between the gears I2 and I6. In order to return to the step-up drive ratio the brake 24 is engaged to stop rotation of the pinion carrier. This requires a braking torque suiilcient to-overcome the friction locking torque of the pinions about their journals. `In practice :it has been found that the pinions lock up so tightly that the torque required of the brake 24 in its slipping `condition in order to break the pinions loose is of such magnitude as to cause considerab'le scuiing of the friction engaging surfaces of the brake. This scuiiing has been eliminated by lubricating the brake surfaces inthe manner hereinafter described. The construction is such *that upon initial engagement of the braking surfaces there is a considerable ow of lubricant between the surfaces and as the slippage gradually decreases the lubricating ow also decreases until, when the brake is positively engaged, the ow of lubricant automaticallyceases.

The brake 24 comprises a series of annular plates 2-6 which are splined at 28 to the outer periphery of 'the cage or pinion carrier I B and an interposed series of annular plates 30 are splined at 32 to an annularV drum 34. The annular drum 34 is resilientlysupported from. a

the drawings in housing structure 36 by an interposed supporting structure 38. A p-air of opposed annular members @il and 42 are secured to each side of the supporting structure 38 by bolts 44 to provide an annular cylindrical space surrounding the series of brake plates 26 and 30. A pair of annular pistons e6 and 48 are sealingly disposed atthe ends Vof 'said annular oylindernforselecting en# gagernent of the brake plates 26 and 30.

The pistons 46 and 48 are provided with a plurality of facing bosses 50 and a plurality of springs 52 are disposed between the pistons 'about these bosses to urge each piston* awayfrorn thel brake plates and toward their respective ends o the cylinder. The annular drum 34 is provided with an outwardly extending flange or tongue 54 having a plurality of openings SSf-tl'irough which tneirinn'ejr ends-tile passages 66 and 68 eommuncit with the l'Illl ylindcl ySpace behind the pistons' and 48 respectively. Therefore, when the' valve 5'! is in its p'eh Aposition aS illustrated, fluid pressureis'supplied to the annular groove ii,transve"r"se passages 52, radial passages et and Ga'tpvtnewaiiiiiilai space behind the leise tons 46 and 4'8- This ui'd pressure urges the pis-` tens 4t and 'da toward each stiletto clamp tlie brake plates together thereby locking the cage erpijnien tangier .against rotation relative to the housing' 36. The brake 24 In'ly be released by Ifn'oving the valve "51 to its dotted line position as illustiateziiii the drawing. In this letter4 pesitien tiie conduit "sa is 'connected to e vent te,

whereby the springs v.52 are operative toV release thebrale. n

In orde'rto lubricate thebr'ak'e' plates `each pisten is V'provided withz e. plurality of 'eiieiiin'fereii-- tially disposed restrictive openings and each ofthe' brake plates' '26 and 30 are 'providedi'with a correslcoriding number V4of similarly located openings 'and 'lj respectively. Each of the openings?? and "lil are provided with .so-called Michel1ed" 'edges 15' to help or otherwise aid the r'ja'dalfl'ow of lubricant 'frein the openings 72 and 1,4 over the Vsurfaces "of the plates 2B and 30. Thatis, the edges of the holes 'l2y and 74 in effect are proyided'with a 'flat bevel. The openingsor holes 19V/in the piston are restricted in size relative tothe oil inletpassages B6 and 6B whereby, when the valve i.iFi is opehed'the oil pressure will immediately bund up beliiiidtne pistonsv te attu-y ate the pistons toward engagement of the brake plates. Because of the relative slip of the brake pletestlie holes 1o, i2, 'energie will line up quite frequently so that tlierelwill be oil flow through these holes and out over the plates from the holes i2 and le to intricate vthe plates.v After the breite plates are -lockedtogeth`e`rnolubrication is necessary so that it is limn'l'aterial Whether the holes are thenalined. If desiredailnulaigrooves inay be p`l^ol`1idedoifik each surface ofthe plates 26 and across the holes 12and "14t insure a 'continuous flow oflubricating oil through and across the lplates 2S and Sllprior to clamping `engage-- ment of these plates, In either construction the' oil ows through the holes 12 and 14 in the various brake plates and escapes radially over the adjacent surfaces of these plates to eiectively lubricate and cool these surfaces This flow of oil over the adjacent surfaces of the plates escapes axially over the .inner and vouter diame'tersfofj these plates and thence through appropriate passages to the engine sump.

As the pressure builds up behind the pistons the plates 2S and 3! are Vsqueezed closer and closer together. The friction torque developed by the brake gradually increases and the escaping flow-ef oil .between the plates is gradually restricted until the plates develop sufficient torqueto unlock the pinions 2B from their jourhals 22.- When this point is reached the plates 26 ande are locked or clamped together and this clamping engagement of the plates shuts off the Vflow of lubricating oil out between the plates.; Passages le formed' inthe -vannular inembers- 49 d2 perr'nit'returnof oil `escaping radially outward .from'theplates :26"ano'l 30.

jhe Aia'bove described' construction Ypro'vidl'es a lubricating 'oilii'ow overthe entire friction 'eng aing surface of `the 'brake plates; 'which oil now will carry away the-"frictional'heat ydevelopedjoy the iterative slippage @fthe-*brake plates. 'The oil pressure' operating, tnejjbrake is preferably derivedffroin 'the engine 'oil pressure Ysyster'n as was Yalsc'i'the 'casei in theaior'eiirlerltionedl copend; ing'application of'liill et al. Howevergyvhenthe brake plates are lubricated their `coeilicie'ent of friction isv considerably reduced -eiid vtnt-metete rn'uch fhigher yfluid pressures are necessary -to effeet-lockiiigengagelnent ofthe brake. There-Y foreja booster 'puinp'rrraii 'be lnecessary irl order tol augment tlie pressure/supplied 'by thev engine iljpre'ssure system.

The'bi'alte 24'has beenjtiescribed in connection with ti-particular transmission; however, it seems obvious `that this brakeiisof vgeneral application aildmay be use'dwherever affliction-clamping tgiioiiegisdesired. 'lv-ne new of nitricatingV eilover the Vjfriction' engaging "surfaces lubricates these surfaces and,r in addition, Y carries away f the 4heat developed-during slippage ofthese surfaces. VIt is 'also' a feature ofY this-invention that the'locke ing engagementof thefri'ction Yengaging' surfaces auteiiietieall'y operates to seal or shut en this lvvf VOil'v'vhent"is nolnige needed. In tlti-t tion, 'the 15(".l"vsi0n` 0f a pistonat btl'l'els ltlie series ef breite plates fil-t and et provides-'foie' uniform torque v'distribution between the various platee and theprei/istituof vineens 'te-feed lubrieating eil throught-ne series et plates-nem beth endsof the series insuresuiiiorrn lubiieatien -e-f al1-the plates. Y n

rI he outer brake drum 34 preferably is resiliently connected 'to the SuDpting'structure-SB -in orner te provide ev radially vtti-iii e teisieiially yieldable suppclirt.l The supperting structure 38 is provided with radially disposed parallel .lianges 1'8 beto/en which the `lflange lportieri 54 of 'the d'rurn '3e adapted to be inter'tted. Ilf'le-innerV diameters di tneflenges is alternately increase and decrease inlagfnitude andthe outerdiametelof the flange "portion 254 is similarly 'tone st'riieted, whereby these ineiiibers maybe axially as'sernl'aled and then rotated to their-nteritted position: The overlapping portions of the ii'anges ell-and Hl are each 'provided with similar cutout portions 3B. Each of these cutout portions is adapted to receive a pair of v.opposed bearing members $32 having'. a spring v84interposed, there;

:Mondeo between. With this construction thefspring 84 permits slight relative rotative and radial movement betweenthe supporting structure 38 and the drum 34,` The purpose of this resilient con.; nection .is to prevent uneven loading of one or more of the pinions 28, It should be noted that the previously described brake can be usedWith or without this resilient supporting structure.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled.V in the art, after understanding my invention, that various changes and modificationsY may be made therein without de parting from the spirit or scope thereof.` I aim in the appended claims to cover all such modiflcations and changes.

I claim as my invention: i

1. In combination, relatively rotatable members having frictionally engageable surfaces, a piston-cylinder assembly for effecting clamping engagement ofsaid surfaces upon the-applicaF tion of oil V pressure thereto, and oil passage means from said assembly communicating with the space between said surfaces to provide for ow of said oil over said surfaces upon the application of oil pressure to said assembly such that clamping engagement of said surfaces is operative to shut off said iiow of oil. Y

2. In combination, a pair of annular relatively rotatable friction discs, a piston-cylinder assembly for effecting clamping engagement of said discs upon the application of oil pressure to said assembly, one or more restricted oil passages extending from said assembly to the adjacent friction disc intermediate the inner and outer diameters of said disc, and cooperating oil passages extending through said adjacent disc whereby, upon application of oil pressure to said piston-cylinder` assembly, oil flows through said passages and out between the engageable surfaces of said discs, the clamping engagement of saidr surfaces being operative to shut off said flow of oil.

:3. In combination with a pair of relatively rotatable members, means to frictionally inhibit relative rotation of said members comprising a multiple disc-type clutch having a plurality of annular friction discs disposed in side-by-side relation and each connected to one or the other of said members such that adjacent discs are connected to different members, piston means engageable with said plurality of discs, means to apply oil pressure to said piston means for effecting clamping engagement of said discs, each of said annular discs having one or more oil passages extending therethrough intermediate their inner and outer diameters, and means for supplying oil into said passages at each end of said plurality of discs simultaneously with the application of oil to said piston means.

4. In combination with a pair of relatively rotatable members, means to frictionally inhibit relative rotation of said members comprising a multiple disctype clutch having a plurality of annular friction discs disposed in side-by-side 65 relation and each connected to one or the other of said membersI such that adjacent discs are connected to different members, piston. means engagea-ble with said plurality of discs, means to apply oil pressure to said piston means for effecting clamping engagement of said discs, each of said annular discs having one or more oil passages extending therethrough intermediate their inner and outer diameters, the ends of each of said passages being .beveled at the faces of each 75 of said members such that adjacent discs are l connected to different members, piston means engageable with each end of said plurality of discs, and means to apply oil pressure simultaneously to each piston for effecting clamping engagement of said discs, each of said piston means having one or more restricted oil passages therethrough to the adjacent disc intermediate the inner and outer diameters of said discs and each of said discshaving'one or more cooperating "oi1 passages 'i extending therethrough intermediateV their inner and outer diameters. i

6. In combination with a pair of relatively rotatable members, means to frictionally inhibit relative rotation of said members comprising a multiple disc-type clutch having a plurality of annular friction discs disposed in side-:by-side relation and each connected to one or the other of said members such that adjacent discs are connected to different members, piston means, means to apply oil pressure to said piston means for eiecting clamping engagement of said discs, and oil passage means extending through said piston and through said plurality of discs intermediate the inner and outer diameters of said discs, whereby, upon application of said oil pressure, oil ows from said passage means over the engageable surfaces of said discs prior to their complete clamping engagement and upon complete engagement of said discs said oil flow is automatically interrupted thereby.

7. In combination with a pair of relatively rotatable members, means to frictionally inhibit relative rotation of said members comprising a multiple disc-type clutch having a plurality of annular friction discs disposed in side-by-side relation and each connected to one or the other of said members such that adjacent discs are connected to different members, piston means, means to apply oil pressure to said piston means for effecting clamping engagement of said discs, and oil passage means spaced from the periphery of said piston means and discs and extending therethrough whereby, upon application of said oil pressure, oil flows from said passage means over the engageable surfaces of said discs prior to their complete clamping engagement and upon complete engagement of'said discssaid oil flow is automatically interrupted thereby.

8. In combination with a pair of relatively rotatable members, means to l'rictionally inhibit relative rotation of said members comprising a multiple disc-type clutch having a plurality of annular friction discs disposed in side-by-side relation and each connected to one or the other of said members such that adjacent discs are connected to different members, piston means engageable with each end of said plurality of discs, means to apply oi1 pressure simultaneously to each piston for effecting clamping engagement of said discs, and oil passage means spaced from the periphery of said piston means and discs and extending therethrough, whereby, upon application of said oil pressure, oil ows from said passage means over the engageable surfaces of said discs lpriorto .compietefclamping engagement of said discs and upon `complete"engagement of said discs said oil iiow .is automatically interrupted thereby. v

I 9. In combinationfa pair of. relatively-rotatable members having.frictionally-engageable surfaces, a source of liquid under pressure, means oper# ative upon the application of said liquid pressure thereto for effecting clamping engagement of said surfaces, liquid passage means fromv said source to said first-mentioned means andA to one or more points on said surfaces and spaced from the edges of said surfaces, 'and valve means operablewr to control saidy passage means to effect application of said liquid pressure from said source to said rst-mentioned means and to simultaneously supply liquid from Asaid source to said one or more points on said surfaces.'

10. In combination, a pair of relatively rotat` i able members having frictionallyengageable surfaces, means operative upon .the application of liquid pressure thereto for effecting clamping frictional engagement 'of said'surfaces, passage means arranged to place a source yof liquid under 8 pressure in vcommunication with .said nrstrneii7 tioned means and withsaid surfaces, and means operable topontrol--said .passage means suchtnat liquid under pressure :fromvsaid source -is transmitted to said first-mentioned means and substantially sirrlultaneouslv is transmitted to said surfaces for oW-thereov'en j 11A. In combination; a pair 'of relatively rotatable members having `frictionalliz engageable surfaces, means'operative upon the application of liquidpressure .thereto for [effect-ing clamping frictionalengagement of said surfaces, 1vpassage means arranged to` place a source of liquid under pressurev in 'communication with said lirst-f mentioned means and with `said surfaces, and means operable to control :said passage means such that liquid under pressure lfrom `said source is transmitted to said mst-mentioned means and substantially 'simultaneously Vis transmitted to sa'd surfaces for Aiiow therebetween suchthat clamping engagement of saidfsurfaceszshutsoff said ow. Y 

